1. Field of the Invention
The present invention relates to an electronic fence system and controlling method and, more specifically, to a system and method in which a pet's activity in a predetermined area is restricted when the pet approaches a confined area. A boundary display signal is produced from the fence wire or a radio boundary display signal is sent to a receiver worn on the pet. The receiver gives a vibration (or vibration accompanied by sound) followed by an electric shock or a shock only to the pet. Therefore, the pet cannot move out of the confined area.
2. Description of the Prior Art
Domestic animals are naturally wild. Thus, if pets are not chained up or a fence for confining pets is not established, they can run away and return to the wild or wander about out of the owner's control.
Most people reserve space (e.g. yard etc.) in which their pet can run freely, and the space is enclosed with a fence including braces and nets. Pets are let loose in the space to run freely.
There are problems, however, in that a fence requires an installation cost, and the fence creates an ill appearance. Further, the fence can be spoiled owing to external forces like wind or rain, and a gap through which pets can pass may be formed. The fence then, requires constant management and maintenance, as well as management personnel and its accompanying cost.
To address these problems, an electric shock method was devised. In the method, a wire is installed within the area and a signal is emitted from the wire. A receiver attached to the pet generates a shock to the pet when it approaches the wire within a certain range. The pet is confined within a boundary in which it can be controlled.
One example of the method in which a wire is installed for sending a signal is disclosed in U.S. Pat. No. 5,967,094. FIG. 1 illustrates the pet confinement system using a wire in accordance with the prior art.
A front yard or garden of a house H has a confined area 2 in which a pet may move about freely. A loop of wire represented by a dashed line is buried in the yard along the boundary of the confined area 2.
The wire 3 is electrically connected to a transmitter 4a placed inside a garage G attached to a house H. The transmitter 4a generates RF boundary signals which are radiated through a buried wire 3. As a pet approaches the wire within a predetermined range, a receiver Sa attached on the pet 1 detects the boundary signal radiated from the wire 3.
When the receiver 5a receives the boundary signal radiated from the wire 3, a shock is applied to pet 1 to cause the pet 1 not to escape from the confined area.
Further, the transmitter 4a has a lightning shelter circuitry provided at the wire 3, for protecting an energy shock such as lightning.
A radio method, as another method, was devised. In this method, a transmitter that radiates radio signals though an antenna is placed in the center of the pet's activity area. If a pet goes far away from the antenna, out of a predetermined range, a radio signal is no longer received and a receiver attached to the pet generates an electrical shock to the pet so that it may not escape from the designated area.
Such a radio method is disclosed in U.S. Pat. No. 5,381,129. FIG. 2 illustrates a pet confinement system by a radio method in accordance with the prior art.
The transmitter 4b is installed in a confined area for a pet 1 inside or near a house H. The transmitter 4b radiates a radio signal to restrict the pet's movement in the confined area according to the predetermined range from the installation point of the transmitter 4b. 
The pet 1 wears a collar/receiver 5b that receives a radio signal emitted from the transmitter 4b. The receiver 5b contains a warning or shock system if the pet 1 wanders near the boundary of the confined area.
The confined area of the pet 1 is divided into several areas, such as a safe area 6, a warning area 7, and a shock area 8. The safe area 6 comprises an area in which the pet 1 receives no stimuli from the receiver 5b and can move freely around. The warning area 7 comprises an area in which the pet 1 moves into the area and receives a warning signal, in the nature of a sound or flashing light, from the receiver 5b. Next, the shock area 8 comprises an area in which the pet 1 moves into the area, and the receiver 5b generates a control signal which is a shock and gives a shock to the pet 1.
Therefore, the pet 1 remains within the safe area 6 but if the pet 1 moves into the warning area 7, it will be warned to move back into the safe area 6. Further, if the pet 1 moves into the shock area 8, a shock may be given to the pet 1 indicating no further moving forward.
The conventional confinement system using a fence or a radio has problems in that since the sound signal is used as the warning, the pet cannot recognize the warning if the pet has hearing loss or the pet is in a noisy circumference.
It has a further problem in that an electric shock is directly given when moving out of the safe area, thus enabling the pet to get an excessive shock.